Hydrocracking catalysts, processes for preparing the same and uses thereof

ABSTRACT

Provided are hydrocracking catalysts comprising a cracking component and a hydrogenation component, wherein, for example: the cracking component comprises at least one molecular sieve present in an amount ranging from 0% to 20% by weight relative to the total weight of the catalyst and at least one amorphous silica-alumina present in an amount ranging from 20% to 60% by weight relative to the total weight of the catalyst; the hydrogenation component comprises at least one hydrogenation metal present in a total amount ranging from 34% to 75% by weight calculated by the mass of oxides, relative to the total weight of the catalyst; and the hydrocracking catalyst has a specific surface area ranging from 150 m 2 /g to 350 m 2 /g and a pore volume ranging from 0.20 cm 3 /g to 0.50 cm 3 /g, such as from 0.30 cm 3 /g to 0.45 cm 3 /g, and the product (M×S) of the percentage amount of the total mass of the hydrogenation metal (M) and the specific surface area (S) is equal to or more than 100 m 2 /g, i.e., M×S≧100 m 2 /g. Also provided are the processes for preparing the hydrocracking catalysts and uses thereof.

This application claims priority under 35 U.S.C. §119 to Chinese Patent Application No. 201010222155.1, filed Jul. 7, 2010.

The present disclosure relates to hydrocracking catalysts, such as single-stage hydrocracking catalysts having a high metal amount and a high selectivity to middle distillates, which can be used for processing heavy distillate oil, processes for preparing the same, and use thereof.

Hydrocracking technology is one of the primary means for cracking heavy oil. It has advantages such as a strong adaptability to raw materials, flexible product schemes, high target product selectivity, excellent product quality, and high added-value. It can also satisfy the market requirements for clean fuel and has become the main secondary refining technology in the twenty-first century.

Single-stage hydrocracking technology has the advantages of simple processing, easy operation, low investment, and stable product selectivity and properties. In the single-stage hydrocracking technology, since the raw material is in direct contact with the single-stage hydrocracking catalyst without any pre-refining treatment or with a simple pre-refining treatment, it is desirable that the single-stage hydrocracking catalyst having a stronger hydrogenating performance and a stronger resistance to impurities. Meanwhile, the crude oil quality becomes worse year by year, and to increase the economic benefits, refineries have begun to process the crude oil with deep vacuum distillation technology, so that the end boiling point of the vacuum distillate is increased from 520° C. to about 600° C. Due to the increases in density, distillation range, molecular weight of the hydrocarbon molecules contained therein, structural complexity, and the amounts of impurities such as sulfur and nitrogen, the difficulties of hydrocracking treatment can be greatly increased, which presents the new challenges for hydrocracking technology and hydrocracking catalysts, in particular new challenges for the single-stage hydrocracking catalyst.

The single-stage hydrocracking catalyst is in direct contact with a plurality of organosulfides and organonitrides. Thus, catalysts having sufficiently high hydrodenitrogenation activity, hydrodesulfurization activity, and hydrosaturation performance may be used to maintain the sufficient catalyst performance. The hydrogenation performance of the hydrocracking catalyst having a conventional metal amount (the total amount of the hydrogenation metal is lower than 30% by weight calculated by the oxides) may be less satisfactory with respect to the actual use requirements on the single-stage hydrocracking catalyst.

Hydrocracking catalysts are generally prepared by the impregnation method, the co-precipitation method, and the comulling method. When the impregnation method is used to load active components, less than desirable values may result for the amount of the active components, the specific surface area, and the pore volume. See Chinese Patent No. 01123767.8, U.S. Pat. No. 6,527,945, Chinese Patent No. 00110016.5, Chinese Patent No. 00109747.4, and U.S. Pat. No. 5,565,088. Co-precipitation methods may be used to obtain hydrocracking catalysts having a very high active metal amount. See U.S. Pat. Nos. 5,086,032 and 4,820,677 and Chinese Patent Application No. 200410050730.9. The catalyst prepared by the co-precipitation method, however, may have a smaller pore volume and specific surface area, and might only be useful for treating distillates lighter than diesel oil. Moreover, since the catalyst prepared by the co-precipitation method may have a low metal utilization, a bad metal dispersion capability, a complex preparation process, and a worse product stability, the catalyst may also have an undesirable performance. The comulling method can be used for preparing catalysts having various active metal amounts. However, the catalysts prepared by the kneading method (comulling method) have a relatively low performance, a low specific surface area, and a low active metal utilization, so that it has been less used.

It is generally desired that the single-stage hydrocracking catalysts have a higher active metal amount and also a higher specific surface area and a pore volume at the same time. However, the aforesaid current methods may be less than desirable in achieving such objectives. Thus, it is desirable to develop a hydrocracking catalyst having a combination of high hydrogenation active metal amount, a high pore volume, and a high specific surface area.

Disclosed herein is a single-stage hydrocracking catalyst that, desirably, can simultaneously have high specific surface area and high metal amounts, while its pore volume remains relatively large and can also be prepared by the impregnation methods disclosed herein.

Disclosed herein is a hydrocracking catalyst comprising at least one cracking component and at least one hydrogenation component, wherein the cracking component comprises at least one molecular sieve present in an amount ranging from 0% to 20% by weight relative to the total weight of the catalyst and at least one amorphous silica-alumina present in an amount ranging from 20% to 60% by weight, relative to the total weight of the catalyst, and the hydrogenation component comprises at least one hydrogenation metal present in a total amount ranging from 34% to 75%, such as from 40% to 60%, by weight calculated by the mass of oxides relative to the total weight of the catalyst. Further disclosed herein is a hydrocracking catalyst having a specific surface area ranging from 150 m²/g to 350 m²/g and a pore volume ranging from 0.20 cm³/g to 0.50 cm³/g, and the product (i.e., M×S) of the percentage amount of the total mass of the hydrogenation metal(s) (i.e., M, for example, M=34%-75%, such as from 40%-60%) and the specific surface area (S) being equal to or more than 100 m²/g, i.e. M×S≧100 m²/g, such as M×S=100−170 m²/g, and further such as M×S=120-160 m²/g.

In one embodiment disclosed herein, the hydrocracking catalyst disclosed herein has an average pore diameter (R) ranging from 7 nm to 15 nm.

In one embodiment disclosed herein, the hydrocracking catalyst may comprise suitable components as required, such as alumina, clay, and/or at least one auxiliary agent chosen from phosphorus, fluorine, boron, titanium, and zirconium.

In one embodiment disclosed herein, the at least one molecular sieve in the hydrocracking catalyst is chosen from Y-type molecular sieves, β-molecular sieves, ZSM-5 molecular sieves, SAPO molecular sieves, and MCM-41 mesoporous sieves, and combinations thereof, such as Y-type molecular sieves and β-molecular sieves. The at least one molecular sieve can be in an amount ranging, for example, from 1% to 10% by weight relative to the total weight of the catalyst. The type and amount of the molecular sieve can be specifically chosen and determined by taking into account raw materials' properties and property goals of product to be obtained.

In one embodiment disclosed herein, the at least one amorphous silica-alumina in the hydrocracking catalyst is the main cracking component and is the place for dispersing a plurality of hydrogenation active metals, so as to obtain a greater pore volume and specific surface area and suitable acid properties. The at least one amorphous silica-alumina may have the following characteristics: a surface area ranging from 400 m²/g to 650 m²/g, such as from 400 m²/g to 550 m²/g, a pore volume ranging from 1.0 cm³/g to 2.0 cm³/g, such as from 1.2 cm³/g to 1.6 cm³/g, a silica mass amount ranging from 20% to 80%, such as from 30% to 65%, by weight relative to the total weight of the at least one amorphous silica-alumina, an average pore diameter ranging from 10 nm to 20 nm, such as from 10 nm to 15 nm, and an infrared acid amount (determined by pyridine adsorption infrared spectroscopy at 160° C.) ranging from 0.3 mmol/g to 0.8 mmol/g.

In one embodiment, the at least one hydrogenation metal in the hydrogenation component of the hydrocracking catalyst disclosed herein is chosen from W, Mo, Ni and Co, such as W and Ni.

The hydrocracking catalyst disclosed herein can be, for example, suitable for the single-stage hydrocracking process.

In the second aspect of the present invention, the hydrocracking catalyst disclosed herein is prepared by the following steps:

-   -   (1) homogeneously mixing the required molecular sieve powder,         amorphous silica-alumina precursor powder, and optional alumina         powder;     -   (2) formulating an impregnating solution containing at least one         hydrogenation active metal component;     -   (3) impregnating the mixed powder in step (1) with the         impregnating solution in step (2);     -   (4) filtering, drying, pulverizing, adding a suitable adhesive         or peptizing agent, molding, drying, and calcining to obtain a         final hydrocracking catalyst.

Other desired components, such as the auxiliary agents, may be added into the solid powder, or the impregnating solution.

In one embodiment of the process for preparing the hydrocracking catalyst, the amorphous silica-alumina precursor is an amorphous gelatinous silica-alumina dry powder prepared by the following steps:

-   -   (1) conducting a neutralization and gelatinization reaction of         an acidic aluminum salt solution (e.g. one or more chosen from         AlCl₃, Al(NO₃)₃, and Al₂(SO₄)₃) with a mixed solution formulated         from an alkaline sodium silicate and sodium aluminate, the         amount of which can be readily determined by one of ordinary         skilled in the art in view of the composition of the final         product, at a temperature ranging from 20° C. to 80° C. and a pH         value ranging from 4.0 to 9.5;     -   (2) adding at least one organosilicon source after         gelatinization, wherein the at least one organosilicon source is         chosen from organic silicon oils and silicon esters; the at         least one organosilicon is added in an amount ranging from 5% to         40% by weight, such as from 10% to 30% by weight, relative to         the total silicon amount required by the final product (i.e.,         relative to the total silicon amount present in the amorphous         gelatinous silica-alumina dry powder), adjusting the pH value         and temperature so as to have an aging temperature ranging from         60° C. to 80° C., a pH value ranging from 6.0 to 10.0, and an         aging time ranging from 60 minutes to 300 minutes;     -   (3) filtering and washing the sol obtained in step (2);     -   (4) drying and pulverizing the filter cake obtained in step (3),         to obtain the amorphous gelatinous silica-alumina dry powder.

In another aspect of the invention disclosed herein, there is a single-stage hydrocracking process, wherein a vacuum distillate such as a vacuum gas oil is in contact with the hydrocracking catalyst disclosed herein in the presence of hydrogen gas.

In one embodiment of the single-stage hydrocracking process disclosed herein, the hydrocracking reaction is conducted at a temperature ranging from 350° C. to 480° C., a reaction pressure ranging from 8 MPa to 20 MPa, a liquid hourly volume space velocity of the vacuum distillate ranging from 0.4 h⁻¹ to 5 h⁻¹, and a hydrogen gas/oil volume ratio ranging from 100:1 to 3,000:1 under the standard condition (i.e., 1 atmosphere and 273.15 K).

In one embodiment of the single-stage hydrocracking process of the present invention, a small amount of a hydrorefining catalyst may be used before and/or after the hydrocracking catalyst is used, for example, the hydrorefining catalyst is used in an amount ranging from 5% to 90%, such as from 30% to 80%, by volume relative to the volume of the hydrocracking catalyst.

In one embodiment of the single-stage hydrocracking process disclosed herein, the vacuum distillate has a final boiling point ranging from 500° C. to 630° C.

Hydrocracking catalyst obtained by using special macroporous amorphous silica-alumina as the dispersion support of the main acidic component and active component and by using a solid powder impregnation method as disclosed herein can have a higher pore volume and specific surface area as well as a higher hydrogenation active component content. The hydrocracking catalyst disclosed herein can have a higher hydrogenation performance, such as hydrodenitrogenation performance, so as to enable the normal exertion of the cracking properties of the single-stage hydrocracking catalyst.

The hydrocracking catalyst disclosed herein can, for example, be prepared by a powder impregnation process. As compared with the conventional impregnation process of the molded support, a powder impregnation process as disclosed herein can absorb more impregnation solution, and have a solution absorption rate of more than 500%. A conventional impregnation process of the molded support has a solution absorption rate of only 100% during the impregnation. Thus the impregnating solution disclosed herein does not need a higher metal concentration. The solution can have a simple formulation and stable properties and can be used in the industrial scale. A more dilute metal salt impregnating solution may decrease the solution viscosity and reduce the surface tension of the solution, so as to weaken the effect of the capillary resistance during the impregnation process. The process disclosed herein may be able to provide a high amount of the metal components in the catalyst and also further increase the dispersion degree of the metal on the support surface.

In an embodiment, the hydrocracking catalyst disclosed herein uses modified molecular sieves and macroporous amorphous silica-alumina supports, and the powder-pulping addition method, described below in the examples can be used for impregnation, which can enable that the catalyst not only has a higher metal amount and a better uniformity of the metal component distribution, but also has a higher pore volume and surface area.

During the preparation of the hydrocracking catalyst disclosed herein, the impregnating solution can be recycled in an embodiment. Such embodiment may result in a simpler preparation process, lower cost, and less pollution, and can be suitable for the industrial scale.

As disclosed herein, in one embodiment, a special Si-modified macroporous alumina having a high pore volume and specific surface area can be used as the support, which may support more metal components and enable the metal components to be better dispersed on the support. A single macroporous alumina support can be used in the process disclosed herein, which can enable that the catalyst not only has a higher metal amount and a better uniformity of the metal component distribution, but also has a higher pore volume and surface area.

In an embodiment, the amorphous silica-alumina used in the catalyst support disclosed herein is prepared by co-precipitating silica and alumina at the same time and introducing organosilicon source as the modified pore-expanding agent after the completion of the gelatinization reaction, which can not only obtain the amorphous silica-alumina having a uniform distribution of silica and alumina, but also increase the Si:Al ratio, pore volume and specific surface area of the amorphous silica-alumina, so as to prepare amorphous silica-alumina having macropores, high specific surface, and high silica-alumina ratio satisfying desired goals of the catalyst performance. Uniform distribution of alumina and silica can also result in uniform distribution of acid centers of the amorphous silica-alumina. After the introduction of organosilicon during the preparation of the amorphous silica-alumina, the organic substances expand and volatilize during the drying and calcining processes, so as to enable the amorphous silica-alumina to obtain a greater pore volume and specific surface. Moreover, the pore volume and specific surface area of the product can be adjusted by adjusting the addition amount of organosilicon according to the actual use requirements.

In another embodiment, during the preparation of the amorphous silica-alumina, pollutants such as ammonia are not used, so that there is no discharge of ammonia nitrogen. The silicon source is the combination of low-cost water glass and a small amount of organosilicon source, so as to effectively control the production cost. Thus, such process can be simple, lower cost, and lower in pollution, and can be suitable for industrial scale preparation.

In yet another embodiment, during the preparation of the amorphous silica-alumina, the silica-alumina ratio of the amorphous silica-alumina product can be flexibly controlled by adjusting the ratio of sodium silicate to sodium aluminate in the alkaline solution, and the ratio of sodium silicate to organosilicon, so as to obtain the amorphous silica-alumina having a broad silica amount ranging from 20% to 80% by weight relative to the total weight of the amorphous silica-alumina. The silica amount in the amorphous silica-alumina has a direct relationship with the acidity, and thus the acidity can be further adjusted to prepare the amorphous silica-alumina materials having different acidities according to different use requirements.

As used herein, the singular form “a,” “an,” and “the” may include plural references unless the context clearly dictates otherwise.

In one embodiment, the process for preparing the catalyst disclosed herein comprises:

-   -   (1) formulating a non-noble hydrogenation metal salt solution,         taking tungsten and nickel as an example: gradually adding         nickel nitrate and ammonium meta-tungstate crystals into a         certain amount of deionized water while stirring, letting it sit         for a sufficient time after the crystals are completely         dissolved, filtering to obtain a metal impregnating solution         having WO₃ in an amount ranging from 10.0 to 50.0 g WO₃/100 ml,         and NiO in an amount ranging from 2.0 to 15.0 g NiO/100 ml. The         formulation processes of the molybdenum-nickel,         molybdenum-cobalt, and three metal component solution, i.e.,         tungsten-molybdenum-nickel, are known in the art;     -   (2) preparing the powdered modified molecular sieves, optional         alumina (as the support), and amorphous silica-alumina: weighing         a certain amount of the components above, which is readily         determined by one of ordinary skill in the art, adding under         stirring into the metal impregnating solution having a         solid-liquid volume ratio ranging from 1:5 to 1:20, pulping for         a period of time ranging from 30 minutes to 120 minutes,         filtering the mixed slurry, controlling the filter cake dry         basis to be from 15% to 30%, drying at a temperature ranging         from 100° C. to 150° C. for 2 to 6 hours to obtain         metal-containing powder having a dry basis being 40%-80%,         pulverizing, and controlling the particle size to be from 100 to         200 mesh. The required molecular sieves may be prepared         according to known methods in the art, or may be chosen from         commercially available products; and other components such as         the required auxiliary agents such as phosphorous, fluorine,         boron, titanium, or zirconium may be added into the solid         powder, or into the impregnating solution;     -   (3) rolling the powder supporting the hydrogenation metal         obtained in step (2), adding a dilute nitric acid solution         having a concentration ranging from 2 g to 10 g HNO₃/100 ml         after a period of time ranging from 20 minutes to 60 minutes,         continuing to roll so as to form an extrudable paste, then         extruding and molding into bars having a length ranging from 3         mm to 8 mm, wherein the catalyst may be in any suitable form,         such as column, clover, four-leaf clover, and any other         heterotypic bar shapes.     -   (4) Drying and calcining the bar obtained in step (3): firstly         drying the bar at a temperature ranging from 100° C. to 150° C.         for a period of time ranging from 2 hours to 6 hours, then         calcining at a temperature ranging from 400° C. to 600° C. for a         period of time ranging from 3 hours to 10 hours to prepare a         catalyst product.

The modified molecular sieve used in the hydrocracking catalyst support as disclosed herein can be chosen from modified Y-type molecular sieves, 13-molecular sieves, ZSM-5 molecular sieves, SAPO molecular sieves, and MCM-41 mesoporous sieves, and combinations thereof. The molecular sieves can be modified by hydrothermal treatment or by chemical dealuminization with EDTA, SiCl₄, (NH₄)₂SiF₆, phosgene, or oxalic acid, or can be modified by a combination of (1) hydrothermal treatment using acidic, alkaline, or salt complexing agents and (2) chemical dealuminization. The modified molecular sieves can have the properties of a silica-alumina molar ratio ranging from 3:1 to 100:1, such as from 10:1 to 60:1, a Na₂O amount of 0.5 wt %, and an infrared acid amount ranging from 0.1 mmol/g to 1.2 mmol/g, such as from 0.2 mmol/g to 0.6 mmol/g.

As disclosed herein, in one embodiment, super-macroporous modified alumina, such as macroporous modified alumina prepared according to Chinese Application No. 200510047483.1, having a pore volume as high as ranging from 1.4 mL/g to 1.8 mL/g and a specific surface area ranging from 500 m²/g to 550 m²/g, can be used as the support component.

In one embodiment disclosed herein, macroporous amorphous silica-alumina has a pore volume as high as that ranging from 1.0 mL/g to 2.0 mL/g, and a specific surface area ranging from 400 m²/g to 650 m²/g. An exemplary process for preparing the macroporous amorphous silica-alumina comprises:

-   -   (1) formulation of an acidic solution, taking the preparation of         AlCl₃ solution as an example: reacting a common alumina with         hydrochloric acid at a temperature ranging from 90° C. to 120°         C., deferrizing, i.e., removing iron, with active carbon to make         the Fe/Al₂O₃ value less than 0.005% by weight and to prepare         fine AlCl₃ solution, and diluting to obtain a solution having         Al₂O₃ concentration ranging from 10 g/L to 60 g/L, which may be         used as the treatment fluid during the gelatinization;     -   (2) formulation of an alkaline solution: formulating NaAlO₂         solution firstly, adding sodium silicate solution while stirring         to prepare a transparent mixed solution containing from 5 g to         80 g Al₂O₃/L and from 5 g to 120 g SiO₂/L;     -   (3) gelatinization process: adding the acidic solution from (1)         and the alkaline solution from (2) at the same time into the         gelatinization tank at a certain flow rate, stirring,         controlling the gelatinization time to range from 60 minute to         100 minutes, controlling the gelatinization reaction temperature         to range from 20° C. to 80° C., such as from 50° C. to 70° C.,         controlling the pH during the gelatinization reaction to range         from 4.0 to 9.5, adding an organosilicon solvent after the         gelatinization reaction, and aging the slurry at a pH ranging         from 6.0 to 10.0 and a temperature ranging from 60° C. to 80° C.         for a period of time ranging from 60 minutes to 300 minutes;     -   (4) filtering and washing: filtering the aged slurry, separating         the mother liquor, washing the resultant filter cake with         deionized water three to five times for a period of time ranging         from 20 minutes to 50 minutes at a controlled temperature         ranging from 60 to 80° C.     -   (5) drying: drying the resultant filter cake in step (4) at a         temperature ranging from 100° C. to 150° C. for a period of time         ranging from 1 hour to 20 hours.

The metal salt solution as disclosed herein generally comprises one or more of the salt solutions of the VIB and/or VIII group metals, such as W, Mo, Ni, Co and the like, wherein the metal solution generally has a concentration ranging from 5.0 g to 50.0 g metal/100 ml.

As disclosed herein, the specific surface area and pore volume are determined by the low-temperature liquid nitrogen physical adsorption method; infrared acid amounts for B acid and L acid are determined by the pyridine adsorption infrared spectroscopy, wherein the total amount of B acid and L acid is the infrared acid amount; the microelements are determined by the plasma emission spectroscopy.

The following examples provide details relating to the process for preparing the support as disclosed herein, but the scope of the present invention is not confined by the examples. The percent amount reported in the examples is the mass percent amount.

EXAMPLE 1 (COMPARISON EXAMPLE)

578 g of macroporous alumina (produced by Tianjin Tianjiu Co., Ltd, having a pore volume of 0.82 ml/g, a specific surface area of 323 m²/g, and a dry basis of 71.1%), and 386 g microporous alumina (SB powder produced by SASOL Germany GmbH) were used to prepare an adhesive (having a dry basis of 26.2%). 6 g of sesbania powder was added, and the resulting mixture was milled for 30 min. A suitable amount of distilled water was added to enable the mixture to be in an extrudable paste form. The mixture was extruded into a bar form, wherein the pore plate of the bar extruder is in a clover form having a diameter of 1.5 mm. The wet bar was dried at 120° C. for 4 h and calcined at 550° C. for 3 h. The resulting support was numbered HF-1S. Two parts of HF-1S support, 120 g for each part, were respectively oversaturatedly impregnated in a tungsten-nickel solution (having WO₃ in an amount of 43.1 g/100 ml and MO in an amount of 7.2 g/100 ml) and a molybdenum-nickel solution (having MoO₃ in an amount of 40.7 g/100 ml and NiO in an amount of 6.5 g/100 ml). After impregnation, each catalyst was calcined at 480° C. to prepare the catalyst products numbered HF-1A and HF-1B respectively.

EXAMPLE 2 (COMPARISON EXAMPLE)

The support numbered HF-2S and the catalysts numbered HF-2A and HF-2B were prepared according to the steps recited in Example 1, except that the macroporous alumina in Example 1 was replaced with a silicon-modified macroporous alumina in the same amount, which was prepared according to the patent application Chinese Patent Application No. 200510047483.1.

EXAMPLE 3 (COMPARISON EXAMPLE)

The support numbered HF-3S and the catalysts numbered HF-3A and HF-3B were prepared according to the steps recited in Example 2, except that the impregnating solutions in Example 2 were changed to (1) a tungsten-nickel solution having WO₃ in an amount of 51.5 g/100 ml, and NiO in an amount of 11.4 g/100 ml; and (2) a molybdenum-nickel solution having MoO₃ in an amount of 50.3 g/100 ml, and NiO in an amount of 12.4 g/100 ml.

EXAMPLE 4 (COMPARISON EXAMPLE)

578 g of macroporous alumina (produced by Tianjin Tianjiu Co., Ltd, having a pore volume of 0.82 ml/g, a specific surface area of 323 m²/g, and a dry basis of 71.1%, which are the same as those in Example 1) was hydrothermally treated for 40 min at a temperature of 560° C. and a vapor pressure of 0.1 MPa. Three metal impregnating solutions were prepared: (1) a tungsten-nickel solution having WO₃ in an amount of 12.1 g/100 ml and NiO in an amount of 2.1 g/100 ml; (2) a molybdenum-nickel solution having MoO₃ in an amount of 11.7 g/100 ml and NiO in an amount of 1.8 g/100 ml; and (3) a tungsten-molybdenum-nickel solution having WO₃ in an amount of 6.3 g/100 ml, MoO₃ in an amount of 7.7 g/100 ml, and NiO in an amount of 2.6 g/100 ml. The hydrothermally treated alumina powder was added into each 800 ml stirring metal impregnating solution, impregnated for 120 min, filtered, dried at 120° C. for 4 h, pulverized, and sifted with 180 mesh. The resulting powder was mixed with a suitable amount of sesbania powder, and a dilute nitric acid having a concentration of 4 g HNO₃/100 ml was added for molding, wherein the pore plate of the bar extruder is in a clover form having a diameter of 1.5 mm. The wet bar was dried at 120° C. for 4 h, calcined at 480° C. for 3 h, and the resulting catalysts were numbered HF-4A, HF-4B and HF-4C respectively.

EXAMPLE 5

The catalysts numbered HF-5A, HF-5B, and HF-5C, all of which are within the scope of the present invention, were prepared according to the process recited in Example 4, except that the macroporous alumina in Example 4 was replaced with the same amount of macroporous gelatinous amorphous silica-alumina powder having a pore volume of 1.32 ml/g, a specific surface area of 485 m2/g, a dry basis of 75.4%, a silica amount of 54.4% (based on the dry basis), an average pore diameter of 12.7 nm, and an infrared acid amount of 0.66 mmol/g; and a suitable amount of microporous alumina adhesive was added during molding.

The macroporous gelatinous amorphous silica-alumina powder was prepared by a process comprising parallel-flow adding dropwise 6,000 ml of a AlCl₃ solution containing 5 g/100 ml of Al₂O₃ and a mixed solution of sodium aluminate and sodium silicate containing 5 g/100 ml of Al₂O₃ and 15 g/100 ml of SiO₂, [whose amount depends on the desired pH value, i.e., 8.0 in the present example, into a stirring gelatinization reaction tank having a temperature of 65° C., maintaining the pH value to be 8.0, the reaction lasting for 40 min until the completion of the dripping of the AlCl₃ solution, continuing to stir for 10 min, adding dropwise 120 ml of tetra ethyl ortho-silicate for 20 minutes, adjusting the slurry pH value to 9.0 with 5% sodium hydroxide solution and aging for 1.5 h, filtering the product, washing three times with a deionized water in a solid/liquid volume ratio of 1:20 at 70° C., drying the resultant filter cake at 120° C. for 3 h to obtain about 1,200 g of macroporous gelatinous amorphous silica-alumina powder.

EXAMPLE 6

The catalysts numbered HF-6A, HF-6B and HF-6C within the scope of the invention were prepared according to the steps recited in Example 5, except that (1) the macroporous alumina in Example 4 was replaced with 578 g of materials containing the macroporous amorphous silica-alumina prepared by the following process and the macroporous alumina in Example 4 in a mass ratio of 4:1, and (2) the three impregnating solutions were replaced with (i) a tungsten-nickel solution having WO₃ in an amount of 18.0 g/100 ml and NiO in an amount of 2.8 g/100 ml, (ii) a molybdenum-nickel solution having MoO₃ in an amount of 17.8 g/100 ml and NiO in an amount of 2.9 g/100 ml, and (iii) a tungsten-molybdenum-nickel solution having WO₃ in an amount of 8.7 g/100 ml, MoO₃ in an amount of 9.9 g/100 ml, and NiO in an amount of 3.5 g/100 ml.

Macroporous amorphous silica-alumina (having the properties of a pore volume of 1.40 ml/g, a specific surface area of 550 m²/g, a dry basis of 74.3%, a silica amount of 40.5% (based on the dry basis), an average pore diameter of 13.6 nm, and an infrared acid amount of 0.61 mmol/g) was prepared by a process comprising parallel-flow adding dropwise 16,000 ml of a AlCl₃ solution containing 5 g/100 ml of Al₂O₃ and a mixed solution of sodium aluminate and sodium silicate containing 5 g/100 ml of Al₂O₃ and 15 g/100 ml of SiO₂, whose amount depends on the desired pH value, i.e., 8.0 in the present example, into a stirring gelatinization reaction tank having a temperature of 65° C., maintaining the pH value at 8.0, the reaction lasting for 40 minutes until the completion of the dripping of the AlCl₃ solution, continuing to stir for 10 minutes, adding dropwise 2,800 ml of organic silicon oil containing 10 g/100 ml of SiO₂ (having a brand No. 5001, produced by Shangyu City Fine Chemical Plant, Zhejiang, China) for 40 minutes, adjusting the slurry pH value to 9.0 with 5% sodium hydroxide solution and aging for 1.5 h, filtering the product, washing three times with deionized water having a solid/liquid volume ratio of 1:20 at 70° C., drying the resultant filter cake at 120° C. for 3 h to obtain about 2,400 g of macroporous gelatinous amorphous silica-alumina powder.

Meanwhile, to the combination of macroporous amorphous silica-alumina and macroporous alumina in the same amounts stated in this Example was added an adhesive, molded, dried at 120° C. for 4 h, calcined at 550° C. for 3 h to obtain a catalyst support numbered HF-3S. Three parts of the HF-3S support were prepared and impregnated respectively two times with the impregnating solutions of HF-6A, HF-6B and HF-6C, wherein the impregnating solutions were the tungsten-nickel solution, the molybdenum-nickel solution, and the tungsten-molybdenum-nickel solution as stated in this Example; the impregnation method involved a first impregnation step, a first drying step at 120° C. for 5 h after the first impregnation, a second impregnation step, a second drying step under the same conditions as the first drying step, and a calcination step at 480° C. for 2 hours. The catalysts numbered HF-6A-1, HF-6B-2 and HF-6C-3 were prepared (HF-6A-1, HF-6B-2 and HF-6C-3 are examples outside of the scope of the present invention as comparison examples.

EXAMPLE 7

The catalysts numbered HF-7A, HF-7B and HF-7C, all of which are within the scope of the present invention, were prepared according to the process recited in Example 5, except that the concentrations of the impregnating solutions in Example 5 were adjusted as follows: (1) the tungsten-nickel solution was adjusted to have WO₃ in an amount of 20.8 g/100 ml and NiO in an amount of 3.4 g/100 ml, (2) the molybdenum-nickel solution was adjusted to have MoO₃ in an amount of 21.3 g/100 ml and NiO in an amount of 4.1 g/100 ml, and (3) the tungsten-molybdenum-nickel solution was adjusted to have WO₃ in an amount of 8.4 g/100 ml, MoO₃ in an amount of 12.1 g/100 ml, and NiO in an amount of 4.3 g/100 ml. In addition, a modified Y molecular sieve (having a silica-alumina molar ratio of 13:1, Na₂O in an amount of equal to or less than 0.1 wt. %, and infrared acid in an amount of 0.8 mmol/g) in an amount of 5% by weight of the final catalyst mass was used.

EXAMPLE 8

The catalysts numbered HF-8A, HF-8B and HF-8C, all of which are within the scope of the present invention, were prepared according to the process recited in Example 5, except that the impregnating solutions were changed to: (1) a tungsten-nickel solution having WO₃ in an amount of 24.3 g/100 ml and NiO in an amount of 4.0 g/100 ml, (2) a molybdenum-nickel solution having MoO₃ in an amount of 25.3 g/100 ml and NiO in an amount of 5.4 g/100 ml, and (3) a tungsten-molybdenum-nickel solution having WO₃ in an amount of 8.9 g/100 ml, MoO₃ in an amount of 15.4 g/100 ml, and NiO in an amount of 4.9 g/100 ml.

The physical and chemical analyses and activity evaluation of the catalysts in each example were conducted, and the physical and chemical properties of the catalysts in each example are listed in Table 1.

TABLE 1 Physicochemical properties of the catalysts No. HF-1A HF-2A HF-3A HF-4A HF-5A HF-6A HF-6A-1 HF-7A HF-8A WO₃, % 23.2 27.9 34.1 26.6 27.1 41.6 41.2 48.2 56.2 NiO, % 5.5 6.4 10.1 6.8 7.5 9.9 10.5 12.1 14.2 Total metal 28.7 34.3 44.2 33.4 34.6 51.5 51.7 60.3 70.4 amount M, % S, m²/g 188 264 200 210 321 261 156 180 153 V, ml/g 0.330 0.401 0.347 0.340 0.454 0.421 0.284 0.340 0.291 R, nm 7.8 9.1 8.0 8.1 11.3 9.7 7.3 7.9 7.3 M × S 54 91 88 70 111 134 81 109 108 No. HF-1B HF-2B HF-3B HF-4B HF-5B HF-6B HF-6B-1 HF-7B HF-8B MoO₃, % 22.9 28.2 35.1 25.7 28.4 42.6 42.5 46.9 54.6 NiO, % 4.9 6.3 9.8 6.5 7.7 11.1 11.3 10.1 16.4 Total metal 27.8 34.5 44.9 32.2 36.1 53.7 53.8 57.0 71.0 amount M, % S, m²/g 197 277 187 234 350 278 168 213 164 V, ml/g 0.354 0.399 0.326 0.421 0.471 0.415 0.276 0.364 0.312 R, nm 8.0 9.4 7.2 9.8 12.1 10.6 6.7 8.4 8.0 M × S 55 96 84 75 126 149 90 121 116 No. HF-4C HF-5C HF-6C HF-6C-1 HF-7C HF-8C WO₃, % 13.4 14.6 18.5 18.2 16.7 20.6 MoO₃, % 14.7 16.4 22.4 23.1 26.1 30.1 NiO, % 5.8 6.9 10.9 10.4 9.7 13.4 Total metal 33.9 37.9 51.8 51.7 52.5 64.1 amount M, % S, m²/g 211 341 286 149 231 200 V, ml/g 0.366 0.424 0.397 0.247 0.350 0.332 R, nm 8.4 11.0 10.1 6.6 9.0 7.9 M × S 72 129 148 77 121 128 V represents pore volume; R represents the average pore diameter.

The evaluation apparatus was a 200 ml small-scale hydrogenation unit, and the catalyst was presulphurized before the activity evaluation. The properties of the raw materials and the technological conditions used for evaluating the catalyst activity are listed in Tables 2 and 3, and the comparison results of relative hydrodenitrogenation activity of the catalysts were listed in Table 4.

TABLE 2 Main properties of the feedstock Density, (20° C.)/g · cm⁻³ 0.9164 Boiling range /° C. IBP/10% 328/376 30%/50% 400/430 70%/90% 455/499 95%/FBP 514/531 Condensation point/° C. 34 Refraction/n_(D) ⁷⁰ 1.4899 Carbon residue, mass % 0.32 S, mass % 1.60 N, mass % 0.1475 IBP: Initial boiling point; FBP: Final boiling point.

TABLE 3 Operating conditions of the pilot plant tests Reaction hydrogen partial pressure, MPa 14.7 Liquid hourly volume space velocity, h⁻¹ 1.0 hydrogen/oil volume ratio 1000:1 Average reaction temperature, ° C. 385

TABLE 4 Comparison results of relative hydrodenitrogenation activity of the catalysts Catalysts HF-1A HF-1B HF-2A HF-3A HF-4A HF-4B HF-4C HF-5A HF-5B HF-5C Relative 100 103 95 94 105 107 102 114 122 118 hydrodenitrogenation activity, % Catalysts HF-6A HF-6B HF-6C HF-6A-1 HF-6B-2 HF-6C-1 HF-7C HF-8A Relative 116 126 123 93 98 96 127 124 hydrodenitrogenation activity, %

TABLE 5 Hydrocracking test results Catalysts HF-6A-1 HF-6B-1 HF-6C-1 HF-6A HF-6B HF-6C HF-7A FC-30*** Average reaction 397 395 395 387 385 386 385 391 temperature, ° C.* Once-through conversion 60 60 60 60 60 60 60 60 rate, mass %** Selectivity of middle-distillate 78 79 79 86 86 87 87 84 yield, mass %** BMCI of tail oil 17 16 16 11 11 10 10 13 *Other conditions were the same as those in Table 3, and the evaluation apparatus was 200 ml small-scale hydrogenation unit. **Once-through conversion rate was the mass percentage of the product having a temperature of less than 370° C. relative to the feedstock; and the selectivity of middle oil was the mass percentage of the product having a temperature of less than 370° C. relative to the reaction product (aviation kerosene + diesel oil). ***FC-30 is a commercial product by Sinopec Group, prepared by a conventional impregnation method. 

1. A hydrocracking catalyst comprising at least one cracking component and at least one hydrogenation component, wherein: the cracking component comprises at least one molecular sieve present in an amount ranging from 0% to 20% by weight relative to the total weight of the catalyst, and at least one amorphous silica-alumina present in an amount ranging from 20% to 60% by weight relative to the total weight of the catalyst; the hydrogenation component comprises at least one hydrogenation metal present in a total amount ranging from 34% to 75% by weight calculated by the mass of oxides, relative to the total weight of the catalyst; and the hydrocracking catalyst has a specific surface area ranging from 150 m²/g to 350 m²/g, a pore volume ranging from 0.20 cm³/g to 0.50 cm³/g, and the product (M×S) of the percentage amount of the total mass of the hydrogenation metal (M) and the specific surface area (S) is equal to or more than 100 m²/g.
 2. The catalyst according to claim 1, wherein the M×S ranges from 100 to 170 m²/g.
 3. The catalyst according to claim 2, wherein the M×S ranges from 120 to 160 m²/g.
 4. The catalyst according to claim 1, wherein the hydrogenation metal is in a total amount ranging from 40% to 60% by weight calculated by the oxide mass, relative to the total weight of the catalyst.
 5. The catalyst according to claim 1, wherein the hydrocracking catalyst has a specific surface area ranging from 160 m²/g to 300 m²/g, and a pore volume ranging from 0.30 cm³/g to 0.45 cm³/g.
 6. The catalyst according to claim 1, wherein the hydrocracking catalyst further comprises alumina, clay, and/or at least one auxiliary agent chosen from phosphorous, fluorine, boron, titanium, and zirconium.
 7. The catalyst according to claim 1, wherein the at least one molecular sieve is chosen from Y-type molecular sieves, β molecular sieves, ZSM-5 molecular sieves, SAPO molecular sieves, and MCM-41 mesoporous molecular sieves.
 8. The catalyst according to claim 1, wherein the at least one molecular sieve is present in an amount ranging from 1% to 10% by weight, relative to the total weight of the catalyst.
 9. The catalyst according to claim 1, wherein the at least one amorphous silica-alumina has a specific surface area ranging from 400 m²/g to 650 m²/g, a pore volume ranging from 1.0 cm³/g to 2.0 cm³/g, a silica amount ranging from 20% to 80% by weight relative to the total weight of the at least one amorphous silica-alumina, an average pore diameter ranging from 10 nm to 20 nm, and an infrared acid amount ranging from 0.3 mmol/g to 0.8 mmol/g.
 10. The catalyst according to claim 1, wherein the at least one amorphous silica-alumina has a specific surface area ranging from 400 to 550 m²/g, a pore volume ranging from 1.2 cm³/g to 1.6 cm³/g, a silica amount ranging from 30% to 65% by weight relative to the total weight of the at least one amorphous silica-alumina, and an average pore diameter ranging from 10 to 15 nm.
 11. The catalyst according to claim 1, wherein the at least one hydrogenation metal is chosen from W, Mo, Ni and Co.
 12. The catalyst according to claim 11, where in the at least one hydrogenation metal is chosen from W and Ni.
 13. The catalyst according to claim 1, prepared by the steps comprising (1) homogeneously mixing an optional molecular sieve powder with an amorphous silica-alumina precursor powder; (2) formulating an impregnating solution comprising at least one hydrogenation active metal; (3) impregnating the mixed powder in step (1) with the impregnating solution in step (2); and (4) filtering, drying, pulverizing, adding an adhesive or a peptizing agent, molding, drying, and calcining to obtain a hydrocracking catalyst.
 14. The catalyst according to claim 13, wherein the amorphous silica-alumina precursor is an amorphous gelatinous silica-alumina dry powder prepared by the steps comprising: (1) conducting a neutralization and gelatinization reaction of an acidic aluminum salt solution with a mixed solution of alkaline sodium silicate and sodium aluminate at a temperature ranging from 20° C. to 80° C. and a pH value ranging from 4.0 to 9.5; (2) adding at least one organosilicon source after gelatinization, wherein the at least one oragnosilicon source is chosen from organic silicon oils and silicon esters; the at least one organosilicon is added in an amount ranging from 5% to 40% relative to the total silicon amount present in the amorphous gelatinous silica-alumina dry powder, having an ageing temperature ranging from 60° C. to 80° C., a pH value ranging from 6.0 to 10.0, and an ageing time ranging from 60 minutes to 300 minutes; (3) filtering and washing the sol obtained in step (2); and (4) drying and pulverizing the filter cake obtained in step (3), to obtain the amorphous gelatinous silica-alumina dry powder.
 15. The catalyst according to claim 1, wherein the catalyst is used for the single-stage hydrocracking process.
 16. The process for preparing a hydrocracking catalyst, comprising the steps of (1) homogeneously mixing an amorphous silica-alumina precursor powder with an optional molecular sieve powder and an optional alumina powder; (2) formulating an impregnating solution comprising at least one hydrogenation active metal component; (3) impregnating the mixed powder in step (1) with the impregnating solution in step (2); and (4) filtering, drying, pulverizing, adding an adhesive or a peptizing agent, molding, drying, and calcining to obtain the hydrocracking catalyst.
 17. The process according to claim 16, wherein the amorphous silica-alumina precursor is an amorphous gelatinous silica-alumina dry powder prepared by the steps comprising (1) conducting a neutralization and gelatinization reaction of an acidic aluminum salt solution with a mixed solution of alkaline sodium silicate and sodium aluminate at a temperature ranging from 20° C. to 80° C. and a pH value ranging from 4.0 to 9.5; (2) adding at least one organosilicon source after gelatinization, wherein the at least one organosilicon source is chosen from organic silicon oils or silicon esters; the at least one organosilicon is added in an amount ranging from 5% to 40% relative to the total silicon amount present in the amorphous gelatinous silica-alumina dry powder, having an ageing temperature ranging from 60° C. to 80° C., a pH value ranging from 6.0 to 10.0, and an ageing time ranging from 60 minutes to 300 minutes; (3) filtering and washing the sol obtained in step (2); and (4) drying and pulverizing the filter cake obtained in step (3), to obtain the amorphous gelatinous silica-alumina dry powder.
 18. A single-stage hydrocracking process, wherein a vacuum gas oil is in contact with the hydrocracking catalyst according to claim 1 in the presence of hydrogen gas.
 19. The single-stage hydrocracking process according to claim 18, wherein the hydrocracking reaction is conducted at a temperature ranging from 350° C. to 480° C. and a pressure ranging from 8 MPa to 20 MPa; with an vacuum gas oil having a liquid hourly volume space velocity ranging from 0.4 h⁻¹ to 5 h⁻¹; and with a volume ratio of hydrogen gas/vacuum gas oil under the standard state ranging from 100:1 to 3,000:1.
 20. The single-stage hydrocracking process according to claim 18, wherein, before and/or after the hydrocracking catalyst is employed, a hydrorefining catalyst is used in an amount ranging from 5% to 90% by volume relative to the volume of the hydrocracking catalyst.
 21. The single-stage hydrocracking process according to claim 18, wherein the hydrorefining catalyst is used in an amount ranging from 30% to 80% by volume relative to the volume of the hydrocracking catalyst.
 22. The single-stage hydrocracking process according to claim 18, wherein the vacuum gas oil has a final boiling point temperature ranging from 500° C. to 630° C. 